Navigating Dependency Injection with Metro

GDG Devfest Incheon 2025와 KUG Seoul KMP Meetup에서 진행한 Metro로 KMP에서 의존성 주입 사용하기의 Speaker Deck입니다.
Thanks for Zac Sweers :)

Transcript

1. Kotlin User Groups Seoul Kotlin Multiplatform Meetup Metro۽ KMPীࢲ ੄ઓࢿ ઱ੑ ࢎਊೞӝ Navigating Dependency Injection with Metro (by Zac Sweers) HyunWoo Lee Kotlin User Groups Seoul Organizer GDG Korea Android Organizer Viva Reupublica(Toss) Android/React Native Developer
2. Kotlin User Groups Seoul Metro۽ KMPীࢲ ੄ઓࢿ ઱ੑ ࢎਊೞӝ HyunWoo Lee
3. Kotlin User Groups Seoul Navigating Dependency Injection with Metro HyunWoo Lee X Zac Sweers
4. Kotlin User Groups Seoul https://speakerdeck.com/l2hyunwoo/navigating- dependency-injection-with-metro Viva Republica Android/React Native Engineer Community & Open Source Lover - GDG Korea Android, Kotlin User Groups Seoul - Contributer & Maintainer Making a new frontier of React Native X Android Granite ❤ Apps In Toss ❤
5. Kotlin User Groups Seoul Dependency Injection (੄ઓࢿ ઱ੑ)
6. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ?
7. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() } }
8. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() val formatter = WeatherFormatter() } }
9. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() val formatter = WeatherFormatter() val forecast = service.getForecast(location) println(formatter.format(forecast)) } }
10. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() val formatter = WeatherFormatter() / / . . . } }
11. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { private val service = WeatherService() private val formatter = WeatherFormatter() fun run(location: String) { / / . . . } }
12. Kotlin User Groups Seoul ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { private val service =aWeatherService() private val formatter = WeatherFormatter() fun run(location: String) { / / . . . } } ࢲ਎ 🌸 24° ب௡ 🇯🇵 25° ׏਄ 🗽 31°
13. Kotlin User Groups Seoul Singletons class WeatherApp { private val service = WeatherService.getInstance() }
14. Kotlin User Groups Seoul Singletons class WeatherApp { private var service = WeatherService.getInstance() inner class Backdoor { fun setService(service: WeatherService) = // ... } }
15. Kotlin User Groups Seoul Service Locator class WeatherApp { private val service: WeatherService = getApplication().getWeatherService() }
16. Kotlin User Groups Seoul Service Locator class WeatherApp { private val service: WeatherService by injector.instance() }
17. Kotlin User Groups Seoul Service Locator class WeatherApp { private val service: WeatherService by inject() }
18. Kotlin User Groups Seoul Service Locator class WeatherApp { private val service: WeatherService by inject() } @Test fun exampleTest() { startKoin { modules( module { single { WeatherService() } }) } / / … }
19. Kotlin User Groups Seoul class WeatherApp { private val service: WeatherService = / /. .. }
20. Kotlin User Groups Seoul class WeatherApp( private val service: WeatherService )
21. Kotlin User Groups Seoul "Don't call us, we'll call you" —The Hollywood Principle
22. Kotlin User Groups Seoul ࣻز ઱ੑ class WeatherApp( private val service: WeatherService )
23. Kotlin User Groups Seoul ࣻز ઱ੑ class WeatherApp( private val service: WeatherService ) @Test fun exampleTest() { val app = WeatherApp(WeatherService()) / / . . . }
24. Kotlin User Groups Seoul ࣻز ઱ੑ class WeatherApp( private val service: WeatherService ) @Test fun exampleTest() { val app = WeatherApp(FakeWeatherService()) / / . . . }
25. Kotlin User Groups Seoul ࣻز ઱ੑ class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) { / / . . . } fun main() { val service = WeatherService() val formatter = WeatherFormatter() val app = WeatherApp(service, formatter) }
26. Kotlin User Groups Seoul ࣻز ઱ੑ class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) { / / . . . } fun main() { val httpClient = HttpClient() val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, app) }
27. Kotlin User Groups Seoul ࣻز ઱ੑ class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) { / / . . . } fun main() { val cache = Cache() val httpClient = HttpClient(cache) val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, app) }
28. Kotlin User Groups Seoul class Cache(…) class HttpClient(private val cache: Cache) class WeatherService(private val httpClient: HttpClient) class WeatherFormatter(…) class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) fun main() { val cache = Cache() val httpClient = HttpClient(cache) val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, app) } ࣻز ઱ੑ
29. Kotlin User Groups Seoul Metroܳ ࣗѐ೤פ׮
30. Kotlin User Groups Seoul ৵ Metroܳ ࣑݅٘աਃ? Dagger-style code gen Kotlin- fi rst Anvil aggrega ti on Mul ti pla tf orm Compiler plugin IDE diagnos ti cs* Metro
31. Kotlin User Groups Seoul ৵ Metroܳ ࣑݅٘աਃ? Dagger-style code gen Kotlin- fi rst Anvil aggrega ti on Mul ti pla tf orm Compiler plugin IDE diagnos ti cs* Metro moshix, RCP Circuit, RCP anvil-ksp compose-lints anvil
32. Kotlin User Groups Seoul Getting Star t ed plugins { id("dev.zacsweers.metro") version "0.6.6" }
33. Kotlin User Groups Seoul Metro DI Constructor/assisted/member/function injection Providers Multibindings Scopes Runtime intrinsics
34. Kotlin User Groups Seoul Metro DI class Cache(…) class HttpClient(private val cache: Cache) class WeatherService(private val httpClient: HttpClient) class WeatherFormatter(…) class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter )
35. Kotlin User Groups Seoul Metro DI @Inject class Cache(…) @Inject class HttpClient(private val cache: Cache) @Inject class WeatherService(private val httpClient: HttpClient) @Inject class WeatherFormatter(…) @Inject class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter )
36. Kotlin User Groups Seoul Metro DI fun main() { val cache = Cache() val httpClient = HttpClient() val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, formatter) }
37. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
38. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp }
39. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp }
40. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } class HttpClient class WeatherFormatter class Cache class WeatherService
41. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } @Component interface AppGraph { val app: WeatherApp }
42. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
43. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
44. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = AppGraph.$$MetroGraph().app }
45. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
46. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @DependencyGraph.Factory interface Factory { fun create(@Provides useMetric: Boolean) : AppGraph } } fun main() { val app = createGraph<AppGraph>().app }
47. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @DependencyGraph.Factory interface Factory { fun create(@Provides useMetric: Boolean) : AppGraph } } fun main() { val app = createGraph<AppGraph>().app }
48. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @DependencyGraph.Factory interface Factory { fun create(@Provides useMetric: Boolean) : AppGraph } } fun main() { val app = createGraphFactory<AppGraph.Factory>() .create(useMetric = true) .app }
49. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp }
50. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() }
51. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache(fs: FileSystem) : Cache = Cache(fs) }
52. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph : CacheProviders { val app: WeatherApp } interface CacheProviders { @Provides fun provideCache(fs: FileSystem) : Cache = Cache(fs) }
53. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() }
54. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideFormatterCache() : Cache = Cache() }
55. Kotlin User Groups Seoul Metro DI @Qualif i er
56. Kotlin User Groups Seoul Metro DI @Qualif i er annotation class Named(val value: String)
57. Kotlin User Groups Seoul Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Named("FormatterCache") @Provides fun provideFormatterCache() : Cache = Cache() }
58. Kotlin User Groups Seoul Metro DI @Named("FormatterCache") Cache
59. Kotlin User Groups Seoul Metro DI @Named("FormatterCache") Cache Type
60. Kotlin User Groups Seoul Metro DI @Named("FormatterCache") Cache Type Quali fi er
61. Kotlin User Groups Seoul Metro DI @Named("FormatterCache") Cache TypeKey
62. Kotlin User Groups Seoul What's a Binding?
63. Kotlin User Groups Seoul What's a Binding? @Provides fun provideCache() : Cache = Cache()
64. Kotlin User Groups Seoul Injection
65. Kotlin User Groups Seoul Injection class HttpClient(private val cache: Cache)
66. Kotlin User Groups Seoul Injection @Inject class HttpClient(private val cache: Cache)
67. Kotlin User Groups Seoul Injection class HttpClient( private val cache: Cache, private val timeout: Duration, ) { @Inject constructor(cache: Cache) : this(cache, 30.seconds) }
68. Kotlin User Groups Seoul Metro DI @Inject class Cache @Inject class HttpClient( private val cache: Cache ) @Inject class WeatherService( private val httpClient: HttpClient ) @Inject class WeatherFormatter @Inject class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
69. Kotlin User Groups Seoul Scoping @Scope
70. Kotlin User Groups Seoul Scoping @Scope annotation class SingleIn(val scope: KClass <*> )
71. Kotlin User Groups Seoul Scoping @SingleIn(AppScope : : class)
72. Kotlin User Groups Seoul Scoping abstract class DataScope private constructor() @SingleIn(DataScope : : class)
73. Kotlin User Groups Seoul Scoping abstract class DataScope private constructor() @SingleIn(DataScope : : class)
74. Kotlin User Groups Seoul Scoping @DependencyGraph interface AppGraph { val app: WeatherApp } @SingleIn(AppScope : : class)
75. Kotlin User Groups Seoul Scoping @SingleIn(AppScope : : class) @DependencyGraph interface AppGraph { val app: WeatherApp }
76. Kotlin User Groups Seoul Scoping @SingleIn(AppScope : : class) @Singleton
77. Kotlin User Groups Seoul Scoping @SingleIn(AppScope : : class) @DependencyGraph interface AppGraph { val app: WeatherApp }
78. Kotlin User Groups Seoul Scoping @Inject class WeatherService( private val httpClient: HttpClient )
79. Kotlin User Groups Seoul Scoping @Inject @SingleIn(AppScope : : class) class WeatherService( private val httpClient: HttpClient )
80. Kotlin User Groups Seoul Scoping @SingleIn(AppScope : : class) @Inject class WeatherService( private val httpClient: HttpClient ) @Inject class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) @DependencyGraph interface AppGraph { val app: WeatherApp } Always same instance
81. Kotlin User Groups Seoul Scoping ӝࠄ੸ਵ۽ ݽٚ bindingҗ Ӓې೐ח scope ૑੿੉ উغয੓਺ Scope੉ ૑੿ػ ߄ੋ٬ٜী ೠ೧ࢲ double-checked lockingਵ۽ ૑ো ୡӝച Scope਷ bindingਸ ੿੄ೞח ଃীࢲ ࢶ঱, ੉ܳ ࢎਊೞח ଃীࢲ scopeਸ ঌ ೙ਃח হ਺ ౠ੿ binding type਷ scope ૑੿ ࠛо
82. Kotlin User Groups Seoul Fun fact: private bindings
83. Kotlin User Groups Seoul More Bindings
84. Kotlin User Groups Seoul @Binds
85. Kotlin User Groups Seoul @Binds interface Bindings { @Binds fun bind(int: Int) : Number @Binds val String.bind: CharSequence }
86. Kotlin User Groups Seoul @Binds @Binds fun bind(int: Int) : Number @Inject class HttpClient(timeoutMillis: Number)
87. Kotlin User Groups Seoul @Binds @Binds fun bind(int: Int) : Number @Inject class HttpClient(timeoutMillis: Number)
88. Kotlin User Groups Seoul @Binds @Binds fun bind(int: Int) : Number @Inject class HttpClient(timeoutMillis: Number)
89. Kotlin User Groups Seoul Assisted Injection
90. Kotlin User Groups Seoul Assisted Injection @Inject class UserRepository( val id: String, val httpClient: HttpClient, val db: UserDb )
91. Kotlin User Groups Seoul Assisted Injection @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb )
92. Kotlin User Groups Seoul Assisted Injection @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb ) { @AssistedFactory interface Factory { fun create(id: String) : UserRepository } }
93. Kotlin User Groups Seoul Assisted Injection @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb ) { @AssistedFactory interface Factory { fun create(id: String) : UserRepository } }
94. Kotlin User Groups Seoul Assisted Injection @Inject class WeatherApp( val factory: UserRepository.Factory ) { fun run() { val userRepo = factory.create("d3938c4891ae") } } @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb ) { @AssistedFactory interface Factory { fun create(id: String) : UserRepository } }
95. Kotlin User Groups Seoul Multibindings @DependencyGraph interface AppGraph { }
96. Kotlin User Groups Seoul Multibindings @DependencyGraph interface AppGraph { val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> }
97. Kotlin User Groups Seoul Multibindings @DependencyGraph interface AppGraph { val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> @Provide @IntoSet fun provideLoggingInterceptor() : Interceptor = LoggingInterceptor() }
98. Kotlin User Groups Seoul Multibindings @DependencyGraph interface AppGraph { val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> @Provide @IntoSet fun provideLoggingInterceptor() : Interceptor = LoggingInterceptor() } @Inject @IntoMap @StringKey("ping") class PingHandler : EventHandler
99. Kotlin User Groups Seoul Multibindings @DependencyGraph interface AppGraph { @Multibinds val interceptors: Set<Interceptor> @Multibinds val eventHandlers: Map<String, EventHandler> }
100. Kotlin User Groups Seoul Multibindings @DependencyGraph interface AppGraph { @Multibinds(allowEmpty = true) val interceptors: Set<Interceptor> @Multibinds(allowEmpty = true) val eventHandlers: Map<String, EventHandler> }
101. Kotlin User Groups Seoul @MapKey Multibindings
102. Kotlin User Groups Seoul @MapKey annotation class ClassKey(val value: KClass <*> ) Multibindings
103. Kotlin User Groups Seoul @MapKey annotation class StringKey(val value: String) Multibindings
104. Kotlin User Groups Seoul @Inject @IntoMap @StringKey("ping") class PingHandler : EventHandler Multibindings
105. Kotlin User Groups Seoul @Provides @ElementsIntoSet fun provideInterceptors() : Set<Interceptor> = setOf(…) Multibindings
106. Kotlin User Groups Seoul Aggregation
107. Kotlin User Groups Seoul Aggregation @DependencyGraph interface AppGraph
108. Kotlin User Groups Seoul Aggregation @DependencyGraph(scope = AppScope : : class) interface AppGraph
109. Kotlin User Groups Seoul Aggregation @DependencyGraph(scope = AppScope : : class) interface AppGraph @SingleIn(scope = AppScope : : class)
110. Kotlin User Groups Seoul Aggregation @DependencyGraph(AppScope : : class) / / @SingleIn(AppScope : : class) / / Implicit! interface AppGraph
111. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache }
112. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @Inject class CacheImpl(…) : Cache
113. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @Inject class CacheImpl(…) : Cache
114. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache @Binds val CacheImpl.bind: Cache } @Inject class CacheImpl(…) : Cache
115. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache
116. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph : CacheImpl.AppScope$$Contribution { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache { @MetroContribution interface AppScope$$Contribution { @Binds val CacheImpl.bind: Cache } }
117. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache
118. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache, Closeable
119. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class, binding = binding<Cache>()) @Inject class CacheImpl(…) : Cache, Closeable
120. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache<Forecast> } @ContributesBinding(AppScope : : class, binding = binding<Cache<Forecast > > ()) @Inject class CacheImpl(…) : Cache<Forecast>, Closeable
121. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache
122. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val interceptors: Set<Interceptor> } @ContributesIntoSet(AppScope : : class) @Inject class LogcatInterceptor(…) : Interceptor
123. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val eventHandlers: Map<String, EventHandler> } @Inject @ContributesIntoMap(AppScope : : class) @StringKey("ping") class PingHandler : EventHandler
124. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph @ContributesTo(AppScope : : class) interface Accessors { val eventHandlers: Map<String, EventHandler> }
125. Kotlin User Groups Seoul What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph : Accessors @ContributesTo(AppScope : : class) interface Accessors { val eventHandlers: Map<String, EventHandler> }
126. Kotlin User Groups Seoul @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> } @ContributesIntoSet(AppScope : : class) @Inject class LogcatInterceptor(…) : Interceptor @Inject @ContributesIntoMap(AppScope : : class) @StringKey("ping") class PingHandler : EventHandler @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache :lib - network :app :lib - events :lib - cache
127. Kotlin User Groups Seoul Intrinsics
128. Kotlin User Groups Seoul Intrinsics Provider Lazy @Inject class HttpClient(val cache: Cache) { init { val cacheInstance = cache } }
129. Kotlin User Groups Seoul Intrinsics Provider Lazy @Inject class HttpClient(val cache: Provider<Cache>) { init { val cacheInstance = cache() } }
130. Kotlin User Groups Seoul Intrinsics Provider Lazy @Inject class HttpClient(val cache: Lazy<Cache>) { init { val cacheInstance = cache.value } }
131. Kotlin User Groups Seoul Graph Extensions
132. Kotlin User Groups Seoul Graph Extensions @GraphExtension interface LoggedInGraph { val user: User }
133. Kotlin User Groups Seoul Graph Extensions @GraphExtension interface LoggedInGraph { val user: User } @DependencyGraph interface AppGraph { val loggedInGraph: LoggedInGraph }
134. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead @GraphExtension interface LoggedInGraph { val user: User } @DependencyGraph interface AppGraph { val loggedInGraph: LoggedInGraph }
135. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead @GraphExtension interface LoggedInGraph { val user: User @GraphExtension.Factory interface Factory { fun create(@Provides id: String) : LoggedInGraph } } @DependencyGraph interface AppGraph { val loggedInGraphFactory: LoggedInGraph.Factory }
136. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead @GraphExtension interface LoggedInGraph { val user: User @GraphExtension.Factory interface Factory { fun createLoggedInGraph() : LoggedInGraph } } @DependencyGraph interface AppGraph : LoggedInGraph.Factory / / usage val loggedInGraph = appGraph.createLoggedInGraph()
137. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead Scope annotations @GraphExtension @SingleIn(LoggedInScope : : class) interface LoggedInGraph { val user: User }
138. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead Scope annotations Aggregation scopes @GraphExtension(LoggedInScope : : class) interface LoggedInGraph { val user: User }
139. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead Scope annotations Aggregation scopes Provider/Binds callables @GraphExtension(LoggedInScope : : class) interface LoggedInGraph { val user: User @Provides fun provideUser() : User = … }
140. Kotlin User Groups Seoul Graph Extensions Factories that you can declare instead Scope annotations Aggregation scopes Provider/Binds callables Their own extensions! @GraphExtension interface LoggedInActivityGraph { val user: User val activity: Activity } @GraphExtension interface LoggedInGraph { val user: User val loggedInActivityGraph: LoggedInActivityGraph } @DependencyGraph interface AppGraph { val loggedInGraph: LoggedInGraph }
141. Kotlin User Groups Seoul Metroח যڌѱ ز੘ೡө? @DependencyGraph interface AppGraph { val app: WeatherApp }
142. Kotlin User Groups Seoul о੢ рױೠ Gradle ౵੉೐ۄੋ @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin .class f i les
143. Kotlin User Groups Seoul ݣ౭೒ۖಬীࢲח? @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin .class .js .wasm . . .
144. Kotlin User Groups Seoul KSP ࠽٘ ౵੉೐ۄੋ @DependencyGraph interface AppGraph { val app: WeatherApp } <compiled binaries> kotlinc (Frontend only) KSP source f i les kotlinc (Frontend and Backend) compileKotlin
145. Kotlin User Groups Seoul kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les KAPTܳ ࢎਊೠ׮ݶ?
146. Kotlin User Groups Seoul kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les javac compileJava More .class f i les KAPTܳ ࢎਊೠ׮ݶ?
147. Kotlin User Groups Seoul kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les javac compileJava More .class f i les HILT ࠽٘ ౵੉೐ۄੋ javac :hiltJavaCompileDebug Even more .class f i les
148. Kotlin User Groups Seoul kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les javac compileJava More .class f i les HILT ࠽٘ ౵੉೐ۄੋ javac :hiltJavaCompileDebug Even more .class f i les
149. Kotlin User Groups Seoul
150. Kotlin User Groups Seoul Metro Build Pipeline @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin binary f i les
151. Kotlin User Groups Seoul Metro Build Pipeline
152. Kotlin User Groups Seoul https://zacsweers.github.io/metro/latest/ per f ormance/
153. Kotlin User Groups Seoul Metro Build Pipeline @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin binary f i les
154. Kotlin User Groups Seoul Metro Build Pipeline binary f i les Frontend Backend Source f i les
155. Kotlin User Groups Seoul Metro Build Pipeline binary f i les Frontend Backend FIR IR Lowering Parse/PSI Source f i les
156. Kotlin User Groups Seoul Metro Build Pipeline binary f i les Frontend Backend FIR IR Lowering Parse/PSI f i r2ir Source f i les
157. Kotlin User Groups Seoul Frontend ࣗझ ౵य ૓ױ(diagnostics) ࠁҊ ஹ౵ੌ ળ࠺о ػ Frontend IR ( FIR) ౟ܻܳ ࠽٘
158. Kotlin User Groups Seoul Frontend Source f i les
159. Kotlin User Groups Seoul Frontend Parse/PSI Source f i les
160. Kotlin User Groups Seoul Frontend FIR Parse/PSI Source f i les
161. Kotlin User Groups Seoul Frontend FIR
162. Kotlin User Groups Seoul Frontend FIR
163. Kotlin User Groups Seoul Frontend FIR Declaration ࢤࢿ Super t ype ࢤࢿ ࢚క ߸ജ
164. Kotlin User Groups Seoul Declaration ࢤࢿ Constructor-injected classes/providers @Inject class Cache { / / Generated by Metro class $$MetroFactory : Factory<Cache> { constructor() companion object { fun create() : $$MetroFactory fun newInstance() : Cache } } }
165. Kotlin User Groups Seoul Declaration ࢤࢿ Constructor-injected classes/providers Assisted factory impls @AssistedFactory interface Factory { fun create(id: String) : UserRepository / / Generated by Metro class $$Impl : Factory }
166. Kotlin User Groups Seoul Declaration ࢤࢿ Constructor-injected classes/providers Assisted factory impls Contribution interfaces @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache { / / Generated by Metro @MetroContribution interface AppScope$$Contribution }
167. Kotlin User Groups Seoul Declaration ࢤࢿ Constructor-injected classes/providers Assisted factory impls Contribution interfaces Etc
168. Kotlin User Groups Seoul Declaration ࢤࢿ @DependencyGraph.Factory interface Factory { fun create() : AppGraph / / Generated in FIR class $$Impl : Factory { constructor() } }
169. Kotlin User Groups Seoul Declaration ࢤࢿ @DependencyGraph.Factory interface Factory { fun create() : AppGraph / / Generated in FIR class $$Impl : Factory { constructor() } } @DependencyGraph.Factory interface Factory { fun create() : AppGraph class $$Impl : Factory { constructor() { } / / Implemented in IR override fun create() : AppGraph = AppGraph.$$MetroGraph() } }
170. Kotlin User Groups Seoul Super t ype ࢤࢿ
171. Kotlin User Groups Seoul Super t ype ࢤࢿ @DependencyGraph(AppScope : : class) interface AppGraph
172. Kotlin User Groups Seoul Super t ype ࢤࢿ @DependencyGraph(AppScope : : class) interface AppGraph @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache { / / Generated by Metro @MetroContribution interface AppScope$$Contribution } @ContributesTo(AppScope : : class) interface NetworkProviders { / / . . . }
173. Kotlin User Groups Seoul ࢚క ߸ജ
174. Kotlin User Groups Seoul Status Transformers
175. Kotlin User Groups Seoul ࢚క߸ജ FirProvidesStatusTransformer FirAccessorOverrideStatusTransformer (Metro 0.6.6+)
176. Kotlin User Groups Seoul Frontend FIR Checkers
177. Kotlin User Groups Seoul Checkers ױ ೞա੄ ୶࢚ ೣࣻ݅ оઉঠ ೞח૑ ೣࣻо dependency graphܳ ߈ജೞח૑ ਬബೠ ഋక੄ ಁ۞޷ఠܳ о૑Ҋ ੓ח૑ …੉৻ীب 100ѐ ؊ object DependencyGraphCreatorChecker
178. Kotlin User Groups Seoul Checkers
179. Kotlin User Groups Seoul Metro Build Pipeline binary f i les Frontend Backend FIR IR Lowering Parse/PSI f i r2ir Source f i les
180. Kotlin User Groups Seoul IR ߸ജ
181. Kotlin User Groups Seoul IR ߸ജ 1. FIRױীࢲ ࢤࢿೠ Binds ೣٜࣻਸ पઁ۽ ҳഅೞӝ 2. Ӓ ৻ী աݠ૑ ݽٚ Ѫٜী ؀ೠ ߸ജ ੘স
182. Kotlin User Groups Seoul Metro IR Pipeline 1. Ӓې೐о ইצ ௿ېझٜਸ ݢ੷ ߸ജ 2. ੄ઓࢿ Ӓې೐ܳ ߸ജ A. Ӓې೐ ҳࢿ ؘ੉ఠ(߄ੋ٬, ܖ౟, GraphExtension) ࣻ૘ B. GraphExtension ୊ܻ C. BindingGraph ࢤࢿ D. ਬബࢿ Ѩࢎ E. IR Ӓې೐ ҳഅ • ߄ੋ٬ٜ ଻ਕ֍ӝ • Tarjan validation(ъೠਃࣗ Ѿ೤ Ѩ ࢎ) + Kahn sorting(ਤ࢚੿۳) • Ѿҗ ߈ജ • ੿۳ػ(top sorted) • ب׳ оמೠ(reachable) • ૑ো୊ܻ೧ঠ ೡ(deferred) ఃٜ
183. Kotlin User Groups Seoul @Inject @SingleIn(AppScope : : class) class WeatherService( httpClient: HttpClient ) @Inject class WeatherFormatter(…) @Inject class WeatherApp( service: WeatherService formatter: WeatherFormatter ) @DependencyGraph @SingleIn(AppScope : : class) interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideHttpClient(cache: Cache) : HttpClient = HttpClient(cache) } Metro IR Pipeline
184. Kotlin User Groups Seoul Metro IR Pipeline @DependencyGraph @SingleIn(AppScope : : class) interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideHttpClient(cache: Cache) : HttpClient = HttpClient(cache) }
185. Kotlin User Groups Seoul Metro IR Pipeline Scope — @SingleIn(AppScope : : class) @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideHttpClient( cache: Cache ) : HttpClient = HttpClient(cache) }
186. Kotlin User Groups Seoul Metro IR Pipeline Scope — @SingleIn(AppScope : : class) IrBinding.Provided — Cache @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideHttpClient( cache: Cache ) : HttpClient = HttpClient(cache) }
187. Kotlin User Groups Seoul Metro IR Pipeline Scope — @SingleIn(AppScope : : class) IrBinding.Provided — Cache IrBinding.Provided — HttpClient @DependencyGraph interface AppGraph { val app: WeatherApp }
188. Kotlin User Groups Seoul Metro IR Pipeline Scope — @SingleIn(AppScope : : class) IrBinding.Provided — Cache IrBinding.Provided — HttpClient Accessor — app: WeatherApp @DependencyGraph interface AppGraph
189. Kotlin User Groups Seoul Metro IR Pipeline WeatherApp
190. Kotlin User Groups Seoul Metro IR Pipeline WeatherApp class WeatherFormatter class WeatherService
191. Kotlin User Groups Seoul Metro IR Pipeline WeatherApp class HttpClient class WeatherFormatter class Cache class WeatherService BindingLookup Cache: IrBinding.Provided HttpClient: IrBinding.Provided
192. Kotlin User Groups Seoul Metro IR Pipeline WeatherApp class HttpClient class WeatherFormatter class Cache class WeatherService
193. Kotlin User Groups Seoul Metro IR Pipeline WeatherApp (IrBinding.ConstructorInjected) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) Cache (IrBinding.Provided) HttpClient (IrBinding.Provided)
194. Kotlin User Groups Seoul Metro IR Pipeline Tarjan's Algorithm WeatherApp (IrBinding.ConstructorInjected) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) Cache (IrBinding.Provided) HttpClient (IrBinding.Provided)
195. Kotlin User Groups Seoul Metro IR Pipeline Tarjan's Algorithm njected) tructorInjected) ctorInjected)
196. Kotlin User Groups Seoul Metro IR Pipeline Kahn's Topo Sor t WeatherApp (IrBinding.ConstructorInjected) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) Cache (IrBinding.Provided) HttpClient (IrBinding.Provided)
197. Kotlin User Groups Seoul Metro IR Pipeline Kahn's Topo Sor t Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
198. Kotlin User Groups Seoul Metro IR Pipeline Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
199. Kotlin User Groups Seoul Metro IR Pipeline @DependencyGraph @SingleIn(AppScope : : class) interface AppGraph { val app: WeatherApp } Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
200. Kotlin User Groups Seoul Metro IR Pipeline class $$MetroGraph : AppGraph { }
201. Kotlin User Groups Seoul Metro IR Pipeline class $$MetroGraph : AppGraph { } Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
202. Kotlin User Groups Seoul Metro IR Pipeline class $$MetroGraph : AppGraph { } ProviderFieldCollector Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
203. Kotlin User Groups Seoul Metro IR Pipeline class $$MetroGraph : AppGraph { } WeatherService ProviderFieldCollector
204. Kotlin User Groups Seoul Metro IR Pipeline Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected) class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> }
205. Kotlin User Groups Seoul Metro IR Pipeline WeatherFormatter (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected) class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider(…) }
206. Kotlin User Groups Seoul Metro IR Pipeline WeatherFormatter (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected) class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider( WeatherService.$$MetroFactory.create( $$HttpClientProvider.create( $$CacheProvider() ) ) ) }
207. Kotlin User Groups Seoul Metro IR Pipeline class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider( WeatherService.$$MetroFactory.create( $$HttpClientProvider.create( $$CacheProvider() ) ) ) override val app: WeatherApp get() = WeatherApp$$MetroFactory.create( this.weatherServiceProvider, WeatherFormatter$$MetroFactory.create() ).invoke() }
208. Kotlin User Groups Seoul Metro IR Pipeline class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider( WeatherService.$$MetroFactory.create( $$HttpClientProvider.create( $$CacheProvider() ) ) ) override val app: WeatherApp get() = WeatherApp$$MetroFactory.create( this.weatherServiceProvider, WeatherFormatter$$MetroFactory.create() ).invoke() }
209. Kotlin User Groups Seoul ੉৻ী ׮ܲ Ѫٜ • ૐ࠙࠽٘-ౠ൤ য֢ప੉࣌ ҙ۲ ઱੄ • createGraph() ৬ createGraphFactory() ഐ୹ ߸ഋ val graph = createGraph<AppGraph>() val graph = AppGraph.$$MetroGraph()
210. Kotlin User Groups Seoul What if validation fails?
211. Kotlin User Groups Seoul What if validation fails?
212. Kotlin User Groups Seoul What if validation fails?
213. Kotlin User Groups Seoul What if validation fails?
214. Kotlin User Groups Seoul Advanced Usage Binding containers @Includes Member injection Valid cycles Optional Top-level function injection Contribution replacements/excludes Compose integration Repor t s Circuit
215. Kotlin User Groups Seoul Interop & Adoption https://zacsweers.github.io/metro/latest/adoption.html
216. Kotlin User Groups Seoul Component Interop @Component interface StartupComponent { val httpClient: HttpClient / / . . . } @DependencyGraph interface AppGraph { @DependencyGraph.Factory interface Factory { fun create( @Includes startupComponent: StartupComponent ) : AppGraph } } https://zacsweers.github.io/metro/latest/adoption.html
217. Kotlin User Groups Seoul Annotations Interop @Component interface StartupComponent { val httpClient: HttpClient } class HttpClient @Inject constructor( val cache: Provider<Cache> ) metro { interop { enableDagger() enableAnvil() } } https://zacsweers.github.io/metro/latest/adoption.html
218. Kotlin User Groups Seoul Custom Code Generators https://zacsweers.github.io/metro/latest/adoption.html
219. Kotlin User Groups Seoul Migration https://zacsweers.github.io/metro/latest/adoption.html
220. Kotlin User Groups Seoul Metro Docs: https://zacsweers.github.io/metro/ API: https://zacsweers.github.io/metro/api/0.x/ Repo: https://github.com/zacsweers/metro Me: https://github.com/l2hyunwoo